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Author ORCID Identifier
Open Access Dissertation
Doctor of Philosophy (PhD)
Year Degree Awarded
Month Degree Awarded
Fatigue is a highly prevalent symptom for older adults with arthritis. Fatigue is a concerning symptom as it is associated with decreased activity and exacerbates co-morbid conditions. Physical activity and sleep quality have been shown to influence arthritis fatigue. However, the relationship between physical activity and sleep quality over time has not been clearly identified.
The purpose of this pilot study was to examine the relationship between physical activity, sleep and arthritis fatigue. This study examined the direct effects and the mediation and moderation of sleep upon fatigue. The study utilized an experimental, longitudinal repeated measures design using mediation and moderation methodology by Barron and Kenny. Older adults (n=24) with moderate arthritis fatigue from New England participated in the study. Physical activity was defined as simple walking. Participants wore an accelerometer for 6 weeks and kept a daily step count log. Fatigue and sleep disturbance were measured using PROMIS instruments at week 1, 4 and 6. In the cross-sectional study at week 1, the results demonstrated there is no mediation and moderation effect of sleep on arthritis fatigue. In the longitudinal study at week 4, the effect of physical activity was increased when the variable, sleep, was added to the model from -.60 to -.83 indicating that sleep mediates the effect of physical activity on arthritis fatigue. In a follow-up longitudinal study at week 6, sleep did not mediate nor moderate the effects of physical activity on fatigue. No moderation of the effect of sleep was identified at week 1, 4 or 6. The study findings indicate that longitudinal designs are helpful to understand the relationships between physical activity, sleep and fatigue. The study results suggest that promoting physical activity and sleep may help with arthritis fatigue over time, however this result appears time limited.
Cody, Jean L., "Mediation and Moderation of Sleep in Arthritis Fatigue" (2020). Doctoral Dissertations. 1978.
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